This invention relates to catheters, and specifically balloon-tipped suction catheters, for aspiration and extirpation of mucus, secretions, and other deposits (hereinafter collectively referred to as "secretions") from the trachea, endotracheal tubes and tracheostomy tubes. In particular, the invention is directed to a catheter having an improved tip structure and an improved suction control structure which allow for the efficient removal of secretions, and which reduce the likelihood of trauma during the removal procedure. The invention also relates to a method for using such a catheter. The balloon-tipped suction catheter, when used in conjunction with a "Y" connector assembly containing a self-sealing diaphragm assembly is able to maintain positive end expiratory pressure ("PEEP") in the lungs.
Tracheobronchial secretions in endotracheal or tracheostomy tubes are usually removed by aspiration. This procedure, in which a suction catheter is passed down an endotracheal tube, may be ineffective, especially when secretions are viscid and adherent to the walls of the tube. Also, in spite of meticulous technique, this procedure is associated with complications. These complications include mucosal damage, hemorrhage and erosion of the tracheal mucosa. These disadvantages occur even in patients with diseases unrelated to pulmonary diseases.
U.S. Pat. No. 3,965,901, Penny et al., discloses a catheter containing side openings on its distal end. These openings are intended to improve the effectiveness of the catheter and reduce tissue damage. U.S. Pat. No. 4,240,433, Bordow, discloses a sharp tipped fluid aspiration needle with an inflatable balloon. The balloon can be inflated and positioned between the sharp tip of the needle and the internal organs during the aspiration procedure to minimize movement of the sharp needle and consequently reduce the risk of accidental puncture.
Another disadvantage of the above-described aspiration method is the inability to maintain PEEP in the lungs. During continuous mechanical ventilation of patients, a common clinical practice involves the use of PEEP wherein the ventilator provides a specific amount of pressure during the expiratory phase of ventilation. It is desirable not to lose the positive pressure established in the lungs during ventilation.
PEEP in the lungs can generally be lost during two steps of the aspiration method described above. First, PEEP may be lost during insertion of the catheter into the endotracheal tube. Exposure of the interior of the tube to atmospheric pressure causes the loss of the positive pressure. Various sealing means for maintaining pressure have been described. One means is a slidable balloon which surrounds the catheter. The catheter is positioned and the balloon is then slid against the opening to close the opening. A disadvantage of this sealing arrangement is that the user must manually move the slidable balloon to create the seal. Another sealing arrangement is described in U.S. Pat. No. 4,416,263, Grimes. Grimes discloses a connector valve assembly intended to maintain PEEP during the insertion and removal of a catheter. A check valve is used to prevent the loss of positive pressure.
Second, PEEP may be lost when suction is applied to the catheter to aspirate the body fluids. In an extreme situation, the conventional suction catheter can cause a lung to collapse due to the negative pressure created by the suction.
Balloon tipped catheters for treating the male urethra, including the prostate gland, have been disclosed. Generally, these catheters are described as being used for injecting or removing fluid from a specified area. One or two balloons are used to isolate the area to be treated. These catheters do not disclose any means for controlling the suction forces to insure that the area downstream of the treated area is not exposed to a vacuum. Control of these forces in the male urethra is not critical like it is in the endotracheal tube. It is important that the lungs are not collapsed by the suction forces applied through the catheter when inserted into the endotracheal tube.
Another problem that is not addressed by the catheters for treating the male urethra is removal of secretions that are strongly adherent to the walls of the passage or tube being cleaned. Secretions in the male urethra, such as pus, are not strongly adherent to the surface on which they lie. Therefore, the male urethra catheters generally describe aspiration as a suitable means for removal of the secretions. Secretions in the endotracheal tube are not easily removed by aspiration because they are strongly adherent to the walls of the endotracheal tube.
The disadvantages of aspiration can be avoided by removal of the secretions by extirpation. Extirpation may be accomplished by the use of a balloon-tipped catheter. The arterial embolectomy catheter sold under the trademark Fogarty.TM. may be used. The catheter is inserted into the endotracheal tube with the balloon deflated. When the desired position is reached, the balloon is inflated until it contacts the sides of the endotracheal tube. The catheter is pulled out of the endotracheal tube with the balloon inflated. As the catheter is withdrawn, the secretions along the walls of the endotracheal tube are displaced by the contact of the balloon against the tube walls. This is commonly referred to as a "squeegee" action. The squeegee action is especially helpful in removing secretions in the endotracheal tubes which are strongly adherent to the tube walls. As the balloon is withdrawn, the secretions accumulate on the proximal side of the balloon. The accumulated secretions are removed when the balloon exits from the endotracheal tube.
A disadvantage of extirpation is the efficiency of secretion removal. The secretions cannot be removed until the balloon has been completely withdrawn from the endotracheal tube. Consequently, the efficiency and ease of secretion removal decreases as the balloon is removed because of the increasing concentration of the secretions on the proximal side of the balloon.
The present invention addresses these disadvantages. This invention provides a balloon-tipped suction catheter and a method for using such a catheter that more efficiently and safely remove secretions from the trachea, endotracheal tubes and tracheostomy tubes. The catheter of the present invention is uniquely designed so that the advantages of both extirpation and aspiration can be utilized.
Another advantage of the present invention is that PEEP can be maintained in the lungs of the patient by using the balloon-tipped suction catheter in combination with a "Y" connector assembly having a self-sealing diaphragm assembly. The seal must be maintained at all times to maintain the pressure in the endotracheal tube. The self-sealing diaphragm assembly of the present invention retains its sealing ability throughout the insertion and removal of the catheter. The user does not have to contend with a sealing means which must be manipulated by the user to insure that the interior of the tube is not exposed to ambient pressure.
A third advantage of the present invention is that the operator can control the transmission of suction forces through the catheter. The operator can insure that suction is not applied at the distal end of the catheter until after the balloon is inflated sealing off the area downstream of the balloon.